Zn2+ adsorption was used to determine the electrochemically active surface area (EASA) of spray pyrolized (SP) film electrodes and of powders prepared by decomposition of metal salts (DMS) in composite graphite and teflon bonded electrodes of spinel oxide Cu1+xMn2-xO4 (0 < x < 0.4) (DMSGT). It is shown that both SP and DMS materials are nanosized with particle diameters in the range 50-80 Angstrom and EASAs per unit loading mass M (EASAM) 1300-2200 cm(2) mg(-1). The lesser intrinsic reactivity in the case of DMSGT electrodes is attributed to modification of the surface reactivity of pure oxide particles in contact with graphite and teflon.